Method for manufacturing inner tubes



Ap '16, 1929. o. J. KUHLKE METHOD FOR MANUFACTURING INNER TUBES Filed Jan. 21, 1927 INVENTOR. 0m: J HM. BY 56? Ban/WW ATTORNEYS Patented Apr. 16, 1929.

UNITED STATES PATENT OFFICE.

OTTO J. KUHLKE, OF AKRON, OHIO, ASSIGNOR TO THE KUHLKE MACHINE COMPANY, OF AKRON, OHIO, A CORPORATION OF OHIO.

METHOD FOR MANUFACTURING INNER TUBES.

Application .filed January 21, 1927. Serial No. 162,468.

This invention relates to a new and improved method of manufacturing inner tubes, the objects of the invention being to secure new and useful advantages over prior methods as will be apparent to those skilled in' the art to which this invention appertains. The method has to do particularly with the formation of tubes from strips or sheets of green or unvulcanized rubber preparatory to vulcanization of the tubes in circular form. Heretofore, in the preparation of the tubes for this method of vulcanization, there has been a marked tendency for the tubes to buckle, increasing the difliculty of placing them in the molds properly and often giving rise to pinched or deformed tubes which have to be discarded or sold as seconds. By the improved process, the green or unvulcanized tube will round itself up due to certain steps in the manufacture, which place certain stresses or tendencies in the tube structure.

The invention also includes the apparatus which is used with the process and is appurtenant thereto.

It will be appreciated that, having ex'- plained the merits and features of the invention, the essential steps thereof may be carried out in other andmodified forms, which it is the intention of the present application to cover as broadly as possible within the limits of the existing art, and as set forth in the claims. 1

In the drawings in which the machine and the various steps of the process are illustrated:

Figure l is a section through a portion of the apparatus with unvulcanized tube constructed thereon;

Figure 2 is a side elevation of the tube removed from the apparatus; and

Figure 3 is a cross section 011 the line 33 of Figure 2. I

The apparatus comprises a ring shaped body or drum 1 which is divided circumferentiallyalong the line 2 into two opposing half sections 3 and 4, one of which sections, here illustrated as section 4, is formedupon or secured to a central spider or support 5 which is intended to be mounted upon a supporting shaft 6 for the purpose of rotating the drum. About the outer periphery of the drum and located equally in both halves thereof is a trough shaped channel or groove 26 which is shaped on approximately the curvature of the inner surface of the tube. The two sections are held together by any suitable means here shown as-lugs 7 through which securing bolts are passed.

At one point about the tube is located the radial aperture 8 for the passage of the valve stem 9, and at a convenient point is arranged a passage 10 which is provided with an attachment for a vacuum or suction line 11 which communicates with the interior of the channel. At certain stages of the operation it is desirable to exert suction upon the inner face of the tube to hold the rubber in place in the cavity 26.' In order to prevent loss of the Vacuum through the valve stem opening 8 a cap may be arranged which is indicated at 12 being fastened to'one of the mold sections 3 as at 14: and being snugly received in the recess in the opposite section.

In the process of building the tube the unvulcanized rubber is cut into strips or sheets one of which is illustrated at 15 and the other at 16. The sheet 15 which is to form the inner portion of the tube is made in ring form, having a diameter not less than and preferably equal to the smallest interior diameter of the tube as shown by the diameter line A. The band 15 is located within the channel, with the valve stem in place, preferably by opening up the drum and stretching the edges of the band up along the sides oft-he channel, the edges of the sheet overlapping and resting upon the outer surface of the drum as shown at 17. In order to hold the band 15 in place in addition to the tendency of the band to contract, suction may be exerted at the surface of the channel upon the interior face of the hand through the passage 10.

The edges of the band are turned over as shown at 18 and the exposed sides thereof are made adhesive by treating with a solvent or cementing and roughening slightly if necessary. The band 16 which is formed in ring shape of the normal diameter larger than the band 15, and preferably of the diameter at about the median line of the tube as indicated at B, is placed over the band 15 and the edges united by'rolling into firm adhesive contact with the surfaces 18.

The tube is now contracted and is removed from the drum by separating the latter. The tube is now ready to be placed within the vulcanizer. \Vhen the tube is removed the tension in the band 15 and its tendency to contract to its normal diameter, which is resisted by the band 16 which is normally of a greater diameter, will cause the tube to assume approximately its correct curvature. The tube may-then be'slightly inflated With air to correctly round it out. The natural shaping of the tube due to its inherent opposing stresses will assist in the placing of the tube in the vulcanizer and will eliminate any tendency to buckle or Wrinkle along its interior circumference. The process which has been described also greatly simplifies methods of producing unvulcanized tubes for curing in circular molds under internal pressure.

What is claimed is:

1. The method of constructing endless circular tubes for vulcanization comprising, forming endless flat bands of unvulcanized rubber, the first of said bands having a normal (unstretched) diameter equal to the inner diameterof the completed tube, and the second band having a somewhat greater normal (unstretched) diameter, shaping the first of said bands to approximately the shape of the inner half of the tube, and uniting the said bands along their edges:

2, The method of constructing endless circular tubes for vulcanization comprising,

forming endless fiat bands of unvulcanized rubber, the first ofsaid bands being less in normal (unstretched) diameter than the second, expanding the edge portions of the first band to approximately the diameter at the median line of the tube, and securing the second band in unstretched condition to the edges of the first band.

3. The method of constructing endless circular tubes for vulcanization comprising, forming endless bands of unvulcanized rubher, the first of said bands having a normal (unstretched) diameter not less than the in ner diameter of the completed tube, shaping the edge portions of the band by stretching outwardly of the tube, the second of said bands having a normal (unstretched) diameter greater than the first band, and placing the second band about the first band and uniting the edges of said band While the first is in stretched condition.

4. The process of constructing endless tubes for vulcanization comprising, forming bands of unvulcanized rubber of diiierent diameters, the smaller being of a diameter equal to the interior diameter of the completed tube, and uniting the hands together along their edges.

o'rro J. UHLKE, 

